Combustor assembly including a transition inlet cone in a gas turbine engine

ABSTRACT

A combustor assembly defining a main combustion zone where fuel and air are burned to create hot combustion products includes a liner, a transition duct, and a transition inlet cone. The liner defines an interior volume including a first portion of the main combustion zone, and has an inlet and an outlet spaced from the inlet in an axial direction. The transition duct includes an inlet section and an outlet section that discharges gases to a turbine section. The inlet section is adjacent to the outlet of the liner and defines a second portion of the main combustion zone. The transition inlet cone is affixed to the transition duct and includes a frusto-conical portion extending axially and radially inwardly into the main combustion zone. The transition inlet cone deflects combustion products that are flowing in a radially outer portion of the main combustion zone toward a combustor assembly central axis.

FIELD OF THE INVENTION

The present invention relates to a combustor assembly in a gas turbineengine and, more particularly, to a combustor assembly including atransition inlet cone between a liner and a transition duct.

BACKGROUND OF THE INVENTION

A conventional combustible gas turbine engine includes a compressorsection, a combustor section including a plurality of combustorassemblies, and a turbine section. The compressor section compressesambient air. The combustor assemblies comprise combustor devices thatmix the pressurized air with a fuel and ignite the mixture to createcombustion products that define working gases. The combustion productsare routed to the turbine section via a plurality of transition ducts.Within the turbine section are a series of rows of stationary vanes androtating blades. The rotating blades are coupled to a shaft and diskassembly. As the combustion products expand through the turbine section,the combustion products cause the blades, and therefore the shaft, torotate.

SUMMARY OF THE INVENTION

In accordance with a first aspect of the present invention, a combustorassembly defining a main combustion zone where fuel and air are burnedto create hot combustion products is provided. The combustor assemblycomprises a liner, a transition duct, and a transition inlet cone. Theliner defines an interior volume including a first portion of the maincombustion zone, and has an inlet and an outlet spaced from the inlet inan axial direction extending parallel to a central axis of the combustorassembly. The transition duct includes an inlet section and an outletsection that discharges gases to a turbine section. The inlet section isadjacent to the outlet of the liner and defines a second portion of themain combustion zone. The transition inlet cone is affixed to thetransition duct and includes a frusto-conical portion extending axiallyand radially inwardly into the main combustion zone. The transitioninlet cone deflects hot combustion products that are flowing in aradially outer portion of the main combustion zone toward the centralaxis of the combustor assembly.

In accordance with a second aspect of the present invention, a combustorassembly defining a main combustion zone where fuel and air are burnedto create hot combustion products is provided. The combustor assemblycomprises a liner, a transition duct, a fuel injection system, and atransition inlet cone. The liner defines an interior volume including afirst portion of the main combustion zone, and has an inlet and anoutlet spaced from the inlet in an axial direction extending parallel toa central axis of the combustor assembly. The transition duct includesan inlet section and an outlet section that discharges gases to aturbine section. The inlet section is immediately adjacent to the outletof the liner and defining a second portion of the main combustion zone.The fuel injection system comprises at least one fuel injector thatinjects fuel into interior volume of the liner for being burned tocreate the hot combustion products. The transition inlet cone includes agenerally cylindrical portion affixed to the transition duct, and afrusto-conical portion joined to the cylindrical portion and extendingaxially and radially inwardly into the main combustion zone at an angleof between about 30 degrees to about 60 degrees relative to the centralaxis such that a radially innermost edge of the transition inlet cone islocated at least about 1 inch from an inner surface of the transitionduct. The transition inlet cone deflects hot combustion products thatare flowing in a radially outer portion of the main combustion zonetoward the central axis of the combustor assembly.

In accordance with a third aspect of the present invention, a retro-fitkit is provided for a gas turbine engine combustor assembly thatincludes a liner and a transition duct downstream from the liner,wherein the liner and the transition duct define a main combustion zonewhere fuel and air are burned to create hot combustion products. Theretro-fit kit comprises a transition inlet cone adapted to be installedin the combustor assembly between the liner and the transition duct fordeflecting hot combustion products flowing in a radially outer portionof the main combustion zone toward a central axis of the combustorassembly during operation of the engine. The transition inlet conecomprises a generally cylindrical portion adapted to be affixed to thetransition duct, and a frusto-conical portion extending axially andradially inwardly from the cylindrical portion into the main combustionzone. The transition inlet cone is adapted to deflect the hot combustionproducts that are flowing in the radially outer portion of the maincombustion zone toward the central axis of the combustor assembly duringoperation of the engine.

BRIEF DESCRIPTION OF THE DRAWINGS

While the specification concludes with claims particularly pointing outand distinctly claiming the present invention, it is believed that thepresent invention will be better understood from the followingdescription in conjunction with the accompanying Drawing Figures, inwhich like reference numerals identify like elements, and wherein:

FIG. 1 is a side cross sectional view of a combustor assembly accordingto an embodiment of the invention; and

FIG. 2 is an enlarged cross sectional view illustrating a transitioninlet cone located between a liner and a transition duct of thecombustor assembly of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

In the following detailed description of the preferred embodiments,reference is made to the accompanying drawings that form a part hereof,and in which is shown by way of illustration, and not by way oflimitation, specific preferred embodiments in which the invention may bepracticed. It is to be understood that other embodiments may be utilizedand that changes may be made without departing from the spirit and scopeof the present invention.

Referring to FIG. 1, a portion of a can-annular combustion system 10 isshown. The combustion system 10 forms part of a gas turbine engine. Thegas turbine engine further comprises a compressor section (not shown)and a turbine section (not shown). Air enters the compressor section,which pressurizes the air and delivers the pressurized air to thecombustion system 10. In the combustion system 10, the pressurized airfrom the compressor section is mixed with a fuel to create an air andfuel mixture, which is ignited to create hot combustion products thatdefine working gases. The hot combustion products are routed from thecombustion system 10 to the turbine section, where they are expanded andcause blades coupled to a shaft and disk assembly to rotate in a knownmanner.

The can-annular combustion system 10 comprises a plurality of combustorassemblies 12. Each combustor assembly 12 comprises a combustor device14, a fuel injection system 16, and a transition duct 18. The combustorassemblies 12 are spaced circumferentially apart from one another in thecan-annular combustion system 10.

Only a single combustor assembly 12 is illustrated in FIG. 1. Eachcombustor assembly 12 forming a part of the can-annular combustionsystem 10 can be constructed in the same manner as the combustorassembly 12 illustrated in FIG. 1. Hence, only the combustor assembly 12illustrated in FIG. 1 will be discussed in detail herein.

The combustor device 14 of the combustor assembly 12 comprises a flowsleeve 20 and a liner 22 disposed radially inwardly from the flow sleeve20. The flow sleeve 20 is coupled to a main engine casing 24 of the gasturbine engine via a cover plate 26 and receives pressurized air thereinfrom the compressor section as will be apparent to those having ordinaryskill in the art. The flow sleeve 20 may be formed from any materialcapable of operation in the high temperature and high pressureenvironment of the combustion system 10, such as, for example, stainlesssteel, and in a preferred embodiment may comprise a steel alloyincluding chromium.

The liner 22 is coupled to the cover plate 26 via a plurality of supportmembers 27 and defines a portion of a main combustion zone 28. That is,the liner 22 defines a first portion 28A of the main combustion zone 28and the transition duct 18 defines a second, downstream portion 28B ofthe main combustion zone 28. As shown in FIG. 1, the liner 22 comprisesan inlet 22A and an outlet 22B spaced from the inlet 22A in an axialdirection A_(D) extending parallel to a central axis C_(A) of thecombustor assembly 12. The liner 22 also has an inner volume 22C, whichdefines the first portion 28A of the main combustion zone 28. The liner22 may be formed from a high-temperature material, such as, for example,HASTELLOY-X (HASTELLOY is a registered trademark of HaynesInternational, Inc.).

The fuel injection system 16 may comprise one or more main fuelinjectors 16A coupled to and extending axially away from the cover plate26 and a pilot fuel injector 16B also coupled to and extending axiallyaway from the cover plate 26. The fuel injection system 16 depicted inFIG. 1 may also typically be referred to as a “main” or a “primary” fuelinjection system, wherein one or more additional fuel injection systems(not shown) may also be provided in the combustor assembly 12. As notedabove, the flow sleeve 20 receives pressurized air from the compressorsection. After entering the flow sleeve 20, the pressurized air movesinto the liner inner volume 22C where fuel from the main and pilot fuelinjectors 16A and 16B is mixed with at least a portion of thepressurized air in the liner inner volume 22C and ignited to create thehot combustion products within the main combustion zone 28.

The transition duct 18 may comprise a conduit having a generallycylindrical inlet section 18A immediately adjacent to the outlet 22B ofthe liner 22, an intermediate section 18B, and a generally rectangularoutlet section (not shown), which discharges the hot combustion productsinto the turbine section. The conduit may be formed from ahigh-temperature capable material, such as a nickel-based metal alloy,for example, HASTELLOY-X, INCONEL 617, or HAYNES 230 (INCONEL is aregistered trademark of Special Metals Corporation, and HAYNES is aregistered trademark of Haynes International, Inc.).

Referring now to FIG. 2, the combustor assembly 12 further comprises atransition inlet cone 32 between the liner 22 and the transition duct18. The transition inlet cone 32 is preferably formed from a differentmaterial than the transition duct 18. For example, the transition inletcone 32 may be formed from an oxide ceramic matrix composite material,such as SiC/SiC or Al₂O₃/Al₂ O₃.

The transition inlet cone 32 includes a generally cylindrical portion 34that is affixed to the transition duct 18 as will be described below,and a frusto-conical portion 36 extending axially and radially inwardlyfrom the cylindrical portion 34 into the main combustion zone 28. Thefrusto-conical portion 36 preferably extends from the cylindricalportion 34 into the main combustion zone 28 at an angle β of betweenabout 30 degrees to about 60 degrees relative to the central axis C_(A),wherein a radially innermost edge 38 of the frusto-conical portion 36 ofthe transition inlet cone 32 is located a radial distance R_(D) of atleast about 1 inch from an inner surface 18C of the transition duct 18.

The transition inlet cone 32 further comprises a radially outwardlyextending flange 40 joined to the cylindrical portion 34 thereof. Theflange 40 is received in a circumferentially extending chamfer 42 formedin the inner surface 18C of the inlet section 18A of the transition duct18. The abutment of the flange 40 to the chamfer 42 serves as an axialstop A_(S) for substantially preventing axial movement between thetransition inlet cone 32 and the transition duct 18.

As shown in FIGS. 1 and 2, the transition inlet cone 32 is secured tothe transition duct 18 via a plurality of pins 46 that extend radiallyfrom the cylindrical portion 34 of the transition inlet cone 32 to theinlet section 18A of the transition duct 18. The pins 46 substantiallyprevent movement, e.g., circumferential and axial movement, between thetransition inlet cone 32 and the transition duct 18. The pins 46 may beformed from a high-temperature capable material, such as a nickel-basedmetal alloy, for example, HASTELLOY-X, INCONEL 617, or HAYNES 230, e.g.,the pins 46 may be formed from the same material as the transition duct18, such that relative thermal expansion between the pins 46 and thetransition duct 18 is substantially avoided. Whether the pins 46 areformed from the same material as the transition duct 18 or not, the pins46 are preferably formed from a material having a higher coefficient ofthermal expansion than that of the transition inlet cone 32, such thatthe transition inlet cone 32 remains tightly in place during operation,e.g., to substantially prevent rattling movement of the transition inletcone 32.

The combustor assembly 12 further includes a contoured spring clipstructure 50 (also known as a finger seal) provided between the outlet22B of the liner 22 and the inlet section 18A of the transition duct 18.The spring clip structure 50 in the illustrated embodiment is providedon an outer surface 22D of the liner outlet 22B (see FIG. 2) andfrictionally engages the inner surface 18C of the transition duct inletportion 18A such that a friction fit coupling is provided between theliner 22 and the transition duct 18. Alternatively, it is contemplatedthat the spring clip structure 50 may be coupled to the inner surface18C of the transition duct inlet portion 18A so as to frictionallyengage the outer surface 22D of the liner outlet 22B. The friction fitcoupling allows movement, i.e., axial, circumferential, and/or radialmovement, between the liner 22 and the transition duct 18, whichmovement may be caused by thermal expansion of one or both of the liner22 and the transition duct 18 during operation of the engine. Forexample, relative movement caused, e.g., by differences in thermalgrowth between the liner 22 and the transition duct 18, may create aforce that overcomes the friction force provided by the spring clipstructure 50 such that substantially unconstrained movement occursbetween the liner 22 and the transition duct 18.

During operation of the engine, the transition inlet cone 32 deflectshot combustion products that are flowing in a radially outer portion 28Cof the main combustion zone 28 toward the central axis C_(A) of thecombustor assembly 12. While this may be advantageous under all engineoperation conditions, it is believed to be particularly advantageousduring less than full load, otherwise known as base load, operatingconditions. That is, pollutants occurring from the combustion process ingas turbine engines are known to be nitrogen oxides (NOx) and carbonmonoxide (CO). Keeping these emission types down to a minimum is animportant requirement in gas turbine engines. CO tends to remain in thecombustion products if there is not enough residence time available,i.e., burning time within the main combustion zone 28 for the combustionproducts, or if the temperature of the combustion products is too lowfor burn-out, which is why the CO emission type becomes a significantissue in part load operation, i.e., where temperatures of the combustionproducts are lower.

It has been found that the temperature of the combustion products in theradially outer portion 28C of the main combustion zone 28 may be lowerthan the temperature of the combustion products near the central axis CAof the combustor assembly 12. Hence, since the transition inlet cone 32of the present invention deflects hot combustion products that areflowing in a radially outer portion 28C of the main combustion zone 28toward the central axis C_(A) of the combustor assembly 12, the coldertemperature combustion products at the radially outer portion 28C of themain combustion zone 28 are forced toward the central axis C_(A) of thecombustor assembly 12 where they are brought to a higher temperature,thus reducing CO emissions.

Further, as shown in FIG. 2, a radial gap R_(G) is formed between thespring clip structure 50 and the transition inlet cone 32. A portion ofthe compressed air from the compressor section located outside of thecombustor assembly 12 that leaks through the spring clip structure 50 isable to pass through the radial gap R_(G) and into the main combustionzone 28 to further assist in pushing hot combustion products away fromthe radially outer portion 28C of the main combustion zone 28 toward thecentral axis C_(A) of the combustor assembly 12, and thus furtherreducing CO emissions.

Additionally, as shown in FIG. 2, the liner 22 includes a conventioncooling system 52. The cooling system 52 comprises a plurality ofaxially ending passages 54 that extend through the liner 22 to the lineroutlet 22B, wherein cooling air, i.e., compressed air from thecompressor section located outside of the combustor assembly 12, passingthrough the passages 54 exits the liner 22 through a plurality ofcircumferentially spaced apart passage outlets 56. The cooling airexiting the liner 22 through the passage outlets 56 flows toward thefrusto-conical portion 36 of the transition inlet cone 32 and furtherassists in pushing hot combustion products away from the radially outerportion 28C of the main combustion zone 28 toward the central axis C_(A)of the combustor assembly 12, and thus further reducing CO emissions.

Moreover, forming the transition inlet cone 32 from an oxide ceramicmatrix composite material has the following advantages. Oxide ceramicmatrix composite materials have very good material properties up totemperatures of around 1200° C., wherein the radially innermost edge 38of the transition inlet cone 32 may be exposed to temperatures of up toabout 1100° C. during operation. For example, while many types ofceramic materials break rather easily, oxide ceramic matrix compositematerials have strong mechanical properties, e.g., similar to thebending strength of steel, since they utilize an elastic core made fromstructural ceramic fibers such as NEXTEL 610 (NEXTEL is a trademark of3M Company). If a metal or nickel base material was used for thetransition inlet cone 32, additional cooling would likely be required onthe backside in order to maintain lifetime expectations of the part.However, by using an oxide ceramic matrix composite material, noadditional cooling is required, which has two advantages. That is, itavoids the use of additional cooling air, which would be required for atransition inlet cone made from a Nickel Base Alloy such as INCONEL orHASTELLOY-X. This prevents an increase of NOx emissions, as this coolingair is still available for the combustion process. And it does not havea negative impact on the efficiency of the gas turbine engine, i.e., theuse of cooling air lowers the temperature of the combustion products,which lowers the efficiency of the engine.

Finally, it is noted that the radial stacking of the components shown inFIG. 2 is as follows: the liner outlet 22B is the radially innermostcomponent, with the spring clip structure 50 being positioned radiallyoutwardly from the liner outlet 22B; the cylindrical portion 34 of thetransition inlet cone 32 is positioned radially outwardly from thespring clip structure 50; and the inlet section 18A of the transitionduct 18 is positioned over the cylindrical portion 34 of the transitioninlet cone 32. This arrangement is particularly advantageous, as thetransition inlet cone 32 is able to be installed into an existingcombustor assembly 12, i.e., one that did not previously include atransition inlet cone 32, with little or no modification of thecomponents of the existing combustor assembly 12. Since typicaltransition ducts 18 may already include the circumferentially extendingchamfer 42, i.e., chamfers 42 are typically created by a counter borethat is machined after forming the transition duct 18 to effect acylindrical inner diameter in the transition duct 18 that the liner 22is capable of being fitted into such that the spring clip structure 50may provide a sealing function as intended, the flange 40 of thetransition inlet cone 32 can efficiently be positioned correctly in theexisting combustor assembly 12. Along these lines, the transition inletcone 32 described herein can be implemented as part of a retro-fit kit60 to be installed into an existing combustor assembly 12.

While particular embodiments of the present invention have beenillustrated and described, it would be obvious to those skilled in theart that various other changes and modifications can be made withoutdeparting from the spirit and scope of the invention. It is thereforeintended to cover in the appended claims all such changes andmodifications that are within the scope of this invention.

What is claimed is:
 1. A combustor assembly defining a main combustionzone where fuel and air are burned to create hot combustion products,the combustor assembly comprising: a liner defining an interior volumeincluding a first portion of the main combustion zone, the liner havingan inlet and an outlet spaced from the inlet in an axial directionextending parallel to a central axis of the combustor assembly; atransition duct having an inlet section and an outlet section thatdischarges gases to a turbine section, the inlet section being adjacentto the outlet of the liner and defining a second portion of the maincombustion zone; a transition inlet cone affixed to the transition ductand including a frusto-conical portion extending axially and radiallyinwardly into the main combustion zone, wherein the transition inletcone deflects hot combustion products that are flowing in a radiallyouter portion of the main combustion zone toward the central axis of thecombustor assembly; a spring clip structure positioned radially betweenthe outlet of the liner and a portion of the transition inlet conethereby forming a radial gap; and wherein the transition inlet conefurther comprises a radially outwardly extending flange joined to thecylindrical portion, and wherein the flange is received in a chamferformed in the inlet section of the transition duct to serve as an axialstop for substantially preventing axial movement between the transitioninlet cone and the transition duct.
 2. A combustor assembly as set outin claim 1, wherein the transition inlet cone further comprises acylindrical portion joined to the frusto-conical portion, and whereinthe transition inlet cone is affixed to the transition duct at thecylindrical portion.
 3. A combustor assembly as set out in claim 2,wherein the transition inlet cone is secured to the transition duct viaa plurality of pins that extend radially from the cylindrical portion ofthe transition inlet cone to the inlet section of the transition duct.4. A combustor assembly as set out in claim 3, wherein the transitioninlet cone is formed from a different material than the transition duct.5. A combustor assembly as set out in claim 4, wherein the transitioninlet cone is formed from an oxide ceramic matrix composite material andthe transition duct is formed from a nickel-based metal alloy.
 6. Acombustor assembly as set out in claim 5, wherein the pins are formedfrom a nickel-based metal alloy.
 7. A combustor assembly as set out inclaim 1, wherein: air from outside of the combustor assembly that leaksthrough the spring clip structure is able to pass through the radial gapand into the main combustion zone to push hot combustion products awayfrom the radially outer portion of the main combustion zone toward thecentral axis of the combustor assembly.
 8. A combustor assembly as setout in claim 1, wherein the frusto-conical portion of the transitioninlet cone extends into the main combustion zone at an angle of betweenabout 30 degrees to about 60 degrees relative to the central axis.
 9. Acombustor assembly as set out in claim 8, wherein the frusto-conicalportion of the transition inlet cone extends into the main combustionzone such that a radially innermost edge of the transition inlet cone islocated at least about 1 inch from an inner surface of the transitionduct.
 10. A combustor assembly defining a main combustion zone wherefuel and air are burned to create hot combustion products, the combustorassembly comprising: a liner defining an interior volume including afirst portion of the main combustion zone, the liner having an inlet andan outlet spaced from the inlet in an axial direction extending parallelto a central axis of the combustor assembly; a transition duct having aninlet section and an outlet section that discharges gases to a turbinesection, the inlet section being immediately adjacent to the outlet ofthe liner and defining a second portion of the main combustion zone; afuel injection system comprising at least one fuel injector that injectsfuel into interior volume of the liner for being burned to create thehot combustion products; and a transition inlet cone including: acylindrical portion affixed to the transition duct; a frusto-conicalportion joined to the cylindrical portion and extending axially andradially inwardly into the main combustion zone at an angle of betweenabout 30 degrees to about 60 degrees relative to the central axis suchthat a radially innermost edge of the transition inlet cone is locatedat least about 1 inch from an inner surface of the transition duct,wherein the transition inlet cone deflects hot combustion products thatare flowing in a radially outer portion of the main combustion zonetoward the central axis of the combustor assembly; and wherein thetransition inlet cone further comprises a radially outwardly extendingflange joined to the cylindrical portion, and wherein the flange isreceived in a chamfer formed in the inlet section of the transition ductto serve as an axial stop for substantially preventing axial movementbetween the transition inlet cone and the transition duct.
 11. Acombustor assembly as set out in claim 10, wherein the transition inletcone is secured to the transition duct via a plurality of pins thatextend radially from the cylindrical portion of the transition inletcone to the inlet section of the transition duct.
 12. A combustorassembly as set out in claim 10, further comprising a spring clipstructure provided between the outlet of the liner and the inlet sectionof the transition duct to provide a friction fit coupling between theliner and the transition duct, wherein the spring clip structure ispositioned radially between the outlet of the liner and a portion of thetransition inlet cone, wherein: a radial gap is formed between thespring clip structure and the portion of the transition inlet cone; andair from outside of the combustor assembly that leaks through the springclip structure is able to pass through the radial gap and into the maincombustion zone to push hot combustion products away from the radiallyouter portion of the main combustion zone toward the central axis of thecombustor assembly.
 13. A retro-fit kit for a gas turbine enginecombustor assembly that includes a liner and a transition ductdownstream from the liner, wherein the liner and the transition ductdefine a main combustion zone where fuel and air are burned to createhot combustion products, the retro-fit kit comprising: a transitioninlet cone adapted to be installed in the combustor assembly between theliner and the transition duct for deflecting hot combustion productsflowing in a radially outer portion of the main combustion zone toward acentral axis of the combustor assembly during operation of the engine,the transition inlet cone comprising: a cylindrical portion adapted tobe affixed to the transition duct; a frusto-conical portion extendingaxially and radially inwardly from the cylindrical portion into the maincombustion zone, wherein the transition inlet cone is adapted to deflectthe hot combustion products that are flowing in the radially outerportion of the main combustion zone toward the central axis of thecombustor assembly during operation of the engine; and wherein thetransition inlet cone further comprises a radially outwardly extendingflange joined to the cylindrical portion, and wherein the flange isadapted to be received in a chamfer formed in the inlet section of thetransition duct to serve as an axial stop for substantially preventingaxial movement between the transition inlet cone and the transitionduct.
 14. A retro-fit kit as set out in claim 13, wherein the transitioninlet cone is adapted to be secured to the transition duct via aplurality of pins that extend radially from the cylindrical portion ofthe transition inlet cone to the inlet section of the transition duct.15. A retro-fit kit as set out in claim 13, wherein: the transitioninlet cone is adapted to be installed in the combustor assembly suchthat a radial gap is formed between the cylindrical portion of thetransition inlet cone and a spring clip structure that is providedbetween an outlet of the liner and an inlet section of the transitionduct to provide a friction fit coupling between the liner and thetransition duct; and air from outside of the combustor assembly thatleaks through the spring clip structure during operation of the engineis able to pass through the radial gap and into the main combustion zoneto push hot combustion products away from the radially outer portion ofthe main combustion zone toward the central axis of the combustorassembly.